The burning of natural gas that is released during drilling, but is deemed not to be economically beneficial to capture. However, methane, the principal component of natural gas is highly flammable as well as a very potent greenhouse gas, and therefore is flared for safety purposes.

Flaring can be useful for controlling certain chemicals that are emitted into the environment, such as converting hydrogen sulphide gas (H2S) into sulphur dioxide (SO2). However, SO2 is known to cause acid rain when it is oxidised further, by reacting with a compound such as nitrogen dioxide. Flares may emit many air pollutants, depending on the chemical composition of the natural gas and the temperature of the flare.